Warheads are often required to penetrate hard concrete or steel targets of either one or multiple layers (walls) and to explode afterwards inside a target cavity. Such warheads have an ogive or a conical nose that assists the penetration by reducing the resistance forces.
This type of warhead is typically made of three sections: (1) a front section, or nose, which is usually in the shape of an ogive or cone; (2) the main section which includes the explosive charge and is usually cylindrical; and (3) the aft section which seals the explosive charge within the casing and holds a penetration fuse for explosive charge initiation.
The warhead which is typically a hollow cylindrically shaped casing, made of high strength steel. Inside the hollow casing lies the explosive charge, and in the rear end of the warhead the penetration fuse is installed. This fuse is designed to initiate the explosive charge at the proper moment, typically, at some predetermined time after the warhead encounters the target.
In penetration warheads, special care is given to the design of the forward penetration nose. The penetration nose must withstand considerable loads, and also, guides the warhead's path through the target (being the first part of the warhead to come in contact with the target), with minimal drag forces. The most widespread approach for penetration nose design is to use a conical or an ogive nose.
When the warhead hits the target at an oblique impact angles, and at the beginning of penetration, asymmetrical forces develop on the conical or ogive nose. Such forces create a rotation moment (torque) around the center of mass of the warhead and cause the warhead to move in a bent line instead of a straight line, or to ricochet, if the warhead hits at shallower impact angles.
This effect is called the J Effect which causes some or all of the following problems: (a) the warhead rotates during target penetration, generating considerable loads on the warhead that may lead to the structural failure of the warhead, (b) the warhead ricochets off the target when the strike angles are shallow, (c) the warhead potential penetration depth of a target is decreased due to bent penetration line, and (d) lateral accelerations acting on the fuse located in the rear part of the warhead increase; such accelerations may cause failure of the fuse during penetration.
The customary design approach to these problems is strengthening the warhead structure by increasing the thickness of the metal and/or changing the kind of metal from which the warhead is made, and strengthening and hardening the warhead fuse to withstand increased side accelerations. This approach has several limitations including an increase in the weight of the weapon system, which is undesirable, reduction of the internal volume for the explosive charge in the warhead and a more complicate design of the penetration fuse. As a result, the cost of the warhead-fuse system increases and its effectiveness decreases.
Another approach is to use a warhead with a blunt nose. This kind of nose reduces the J Effect by creating an opposing force at the beginning of the penetration which balances the moment (torque), but creates much bigger drag forces during the penetration. As a result of the bigger drag forces, some or all of the following problems may develop:                Reduced penetration capability, especially in perpendicular penetration angles because of the configuration of the nose which significantly increase the drag forces on it.        Increase of the accelerations along the axis of the warhead, due to the increased resistance or drag forces, which also negatively affect the warhead and the fuse.        
Thus, warheads of this kind are limited to strikes at relatively shallow angles and into relatively thin targets only.
In view of the above, an aim of the present invention is to provide an improved warhead that overcomes the drawbacks of the above warheads, i.e., a warhead with a nose having a shape which would reduce the J Effect in a situation of a strike at oblique angles, increase the penetration capability and reduce the loads on the warhead and the fuse, without significant increase of penetration drag.
Another aim of the present invention is to provide a missile warhead having high durability while penetrating multi-layered structural targets, without a significant increase in weight.
Yet, another aim of the present invention is to provide a warhead nose that prevents the warhead from ricocheting off structural targets and assists in target penetration, when shallow approach angles and high angles of attack are reached.